An information display system described in Patent Literature 1 connects an apparatus for vehicle and a mobile terminal, and causes the apparatus for vehicle to display a screen of the mobile terminal. In this information display system, when the apparatus for vehicle and the mobile terminal are connected to each other via communications, only one of the apparatus for vehicle and the mobile terminal on which an input operation has been previously performed is enabled to be operated while the one on which an input operation has been previously performed is operated. Therefore, also when the mobile terminal and the apparatus for vehicle are operated by two persons during the same time period, only one of them which has been previously operated is enabled to be operated and a malfunction can be prevented from being caused due to simultaneous operations on them by two persons.